CVE-2026-23457 in Kernel

Sumário (Inglês)

In the Linux kernel, the following vulnerability has been resolved:

netfilter: nf_conntrack_sip: fix Content-Length u32 truncation in sip_help_tcp()

sip_help_tcp() parses the SIP Content-Length header with
simple_strtoul(), which returns unsigned long, but stores the result in
unsigned int clen. On 64-bit systems, values exceeding UINT_MAX are
silently truncated before computing the SIP message boundary.

For example, Content-Length 4294967328 (2^32 + 32) is truncated to 32,
causing the parser to miscalculate where the current message ends. The
loop then treats trailing data in the TCP segment as a second SIP
message and processes it through the SDP parser.

Fix this by changing clen to unsigned long to match the return type of
simple_strtoul(), and reject Content-Length values that exceed the
remaining TCP payload length.

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Responsável

Linux

Reservar

13/01/2026

Divulgação

03/04/2026

Estado

Confirmado

Inscrições

VulDB provides additional information and datapoints for this CVE:

ID	Vulnerabilidade	CWE	Exp	Con	CVE
355136	Linux Kernel SDP Parser sip_help_tcp Autenticação fraca	345	Não definido	Correção oficial	CVE-2026-23457

Fontes

• MITRE
• NVD
• CVE Details